U.S. patent number 4,985,592 [Application Number 05/952,111] was granted by the patent office on 1991-01-15 for process for the preparation of unsaturated carboxylic acids.
This patent grant is currently assigned to Mitsubishi Rayon Company, Ltd.. Invention is credited to Hiromichi Ishii, Kazuhiro Ishii, Masao Kobayashi, Hideo Matsuzawa.
United States Patent |
4,985,592 |
Ishii , et al. |
January 15, 1991 |
Process for the preparation of unsaturated carboxylic acids
Abstract
The gas phase catalytic oxidation of an unsaturated aldehyde
with molecular oxygen at 200.degree. to 500.degree. C. to give the
corresponding unsaturated carboxylic acid is conducted in the
presence of a catalyst represented by the following formula:
wherein the subscripts represent the atomic ratios of each
component and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6, d is 0
to 6, and e is a value determined by the valencies of the elements
present in the catalyst; and Mo is molybdenum, P is phosphorus, O
is oxygen, X is at least one metal selected from the group
consisting of rhodium, cerium and zirconium, Y is at least one
alkali metal selected from the group consisting of potassium,
rubidium and cesium, and Z is at least one metal selected from the
group consisting of iron, cobalt, nickel, zinc, antimony, silicon,
bismuth, cadmium, uranium, manganese, copper, vanadium, niobium and
tantalum. This catalyst is especially effective for the preparation
of methacrylic acid from methacrolein and has a very long life
time.
Inventors: |
Ishii; Hiromichi (Otake,
JP), Matsuzawa; Hideo (Otake, JP),
Kobayashi; Masao (Otake, JP), Ishii; Kazuhiro
(Otake, JP) |
Assignee: |
Mitsubishi Rayon Company, Ltd.
(Tokyo, JP)
|
Family
ID: |
26369504 |
Appl.
No.: |
05/952,111 |
Filed: |
October 17, 1978 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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666565 |
Mar 15, 1976 |
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Foreign Application Priority Data
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Mar 17, 1975 [JP] |
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50-31055 |
Aug 1, 1975 [JP] |
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50-94512 |
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Current U.S.
Class: |
562/534; 502/209;
562/536 |
Current CPC
Class: |
B01J
23/002 (20130101); B01J 23/28 (20130101); B01J
23/34 (20130101); B01J 23/8872 (20130101); B01J
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23/8877 (20130101); B01J 23/8993 (20130101); B01J
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57/04 (20130101); B01J 2523/00 (20130101); B01J
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2523/51 (20130101); B01J 2523/57 (20130101); B01J
2523/68 (20130101); B01J 2523/822 (20130101); B01J
2523/00 (20130101); B01J 2523/13 (20130101); B01J
2523/51 (20130101); B01J 2523/68 (20130101); B01J
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Current International
Class: |
B01J
23/16 (20060101); B01J 23/28 (20060101); B01J
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23/76 (20060101); B01J 23/34 (20060101); B01J
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23/89 (20060101); C07C 51/25 (20060101); C07C
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057/055 () |
Field of
Search: |
;562/534 ;252/435,437
;502/209 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Garner; Vivian
Attorney, Agent or Firm: Oblon, Spivak, McClelland, Maier
& Neustadt
Parent Case Text
This is a continuation of application Ser. No. 666,565, filed Mar.
15, 1976, now abandoned.
Claims
What is claimed as new and intended to be covered by Letters Patent
is:
1. A process for the preparation of unsaturated carboxylic acids,
which comprises catalytically oxidizing acrolein or methacrolein in
the gas phase at a temperature of 200.degree. to 500.degree. C.
with molecular oxygen to form the corresponding unsaturated
carboxylic acids in the presence of a catalyst of the following
formula:
wherein the subscripts represent the atomic ratio of each component
and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6, d is 0 to 6, and
e is a value determined by the valencies of the elements present in
the catalyst; and wherein Mo is molybdenum, P is phosphorus, O is
oxygen, X is rhodium, Y is at least one alkali metal selected from
the group consisting of potassium, rubidium and cesium, and Z is at
least one metal selected from the group consisting of iron, cobalt,
nickel, zinc, antimony, silicon, bismuth, cadmium, uranium,
manganese, copper, vanadium, niobium and tantalum.
2. The process of claim 1, wherein the atomic ratio of the element
Z is 0.01 to 6 when molybdenum is 12.
3. The process of claim 1, wherein the unsaturated aldehyde is
methacrolein.
4. A process for the preparation of unsaturated carboxylic acids,
which comprises:
catalytically oxidizing acrolein or methacrolein in the gas phase
at a temperature of 200.degree. to 500.degree. C. with molecular
oxygen to form the corresponding unsaturated carboxylic acid in the
presence of a catalyst of the formula:
wherein the subscripts represent the atomic ratio of each component
and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6, d is 0 to 6, and
e is a value determined by the valencies of the elements present in
the catalyst; and wherein Mo is molybdenum, P is phosphorus, O is
oxygen, X is rhodium, Y is at least one alkali metal selected from
the group consisting of potassium, rubidium and cesium, and Z is at
least one metal selected from the group consisting of iron, cobalt,
nickel, zinc, antimony, silicon, bismuth, cadmium, uranium,
manganese, copper, vanadium, niobium and tantalum, wherein said
catalyst is prepared by forming a mixed oxide catalyst from the
oxides, chlorides, nitrates, ammonium salts or heteropoly acids of
the elemental constituents of said catalyst, and
calcining said mixed oxide catalyst in an inert gas atmosphere at a
temperature of 300.degree. to 600.degree. C. for at least one
hour.
5. The process of claim 4, wherein said inert gas is nitrogen,
ammonia, carbon dioxide, carbon monoxide, a hydrocarbon, helium or
argon.
6. The process of claim 5, wherein said inert gas is nitrogen.
7. A process for the preparation of unsaturated carboxylic acids,
which comprises catalytically oxidizing acrolein or methacrolein in
the gas phase at a temperature of 200.degree. to 500.degree. C.
with molecular oxygen to form the corresponding unsaturated
carboxylic acids in the presence of a catalyst of the following
formula:
wherein the subscripts represent the atomic ratio of each component
and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6 and e is a value
determined by the valencies of the elements present in the catalyst
and wherein Mo is molybdenum, P is phosphorus, O is oxygen, X is
rhodium and Y is at least one alkali metal selected from the group
consisting of potassium, rubidium and cesium.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a process for preparing unsaturated
carboxylic acids from unsaturated aldehydes in the presence of a
phosphorus-molybdenum-alkali metal type catalyst.
2. Description of the Prior Art
Various catalysts have been known as being suitable for the gas
phase catalytic oxidation of unsaturated aldehydes.
These include, for example, processes for preparing acrylic acid
from acrolein by using a catalyst consisting of P, Mo and As
(Japanese Patent publication No. 19260/1963) or by using a catalyst
consisting of Mo, V, W and silicon (Japanese Patent publication No.
12129/1969). Some of these catalysts have been used on a commercial
scale.
Many processes have also been suggested for preparing methacrylic
acid. These include, for example, Japanese Patent publication No.
6605/1972 (a Mo-Ni-Ti catalyst) and No. 10773/1973 (a catalyst
containing Mo and Tl); U.S. Pat. No. 3,686,294 (a P-Mo-As catalyst)
and No. 3795703 (a P, Mo and alkali metal type catalyst); and
Belgian Patent No. 817100 (a P, Mo and Sb type catalyst). From the
viewpoint of industrial suitability, however, these catalysts are
quite insufficient regarding selectivity and lifetime.
Consequently, there is still a need for improved catalysts for
preparation of methacrolein and/or acrolein.
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a
novel catalyst having a long lifetime suitable for preparing
acrylic acid or methacrylic acid from acrolein or methacrolein.
Briefly, this and other objects of this invention as will
hereinafter be made clear have been attained by providing a process
for the preparation of acrylic acid or methacrylic acid which
comprises catalytically oxidizing acrolein or methacrolein in the
gas phase at a temperature of 200.degree. to 500.degree. C. with
molecular oxygen in the presence of a catalyst of the following
formula:
wherein the subscripts represent the atomic ratio of each component
and a is 0.5 to 6, b is 0.001 to 6, c is 0.2 to 6, d is 0 to 6, and
e is a value determined by the valencies of the elements present in
the catalyst; and wherein Mo is molybdenum, P is phosphorus, O is
oxygen, X is at least one metal selected from the group consisting
of rhodium, cerium and zirconium, Y is at least one alkali metal
selected from the group consisting of potassium, rubidium and
cesium and Z is at least one metal selected from the group
consisting of iron, cobalt, nickel, zinc, antimony, silicon,
bismuth, cadmium, uranium, manganese, copper, vanadium, niobium and
tantalum.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
A practical catalyst high in activity, selectivity and lifetime and
suitable for use in a process for preparing methacrylic acid from
methacrolein has now been discovered. It has been further
discovered that this catalyst can be also used in a process for
preparing acrylic acid from acrolein.
In the catalyst to be used in the present invention, the chemical
states of phosphorus, molybdenum, the alkali metal and the other
metals are so complicated that the chemical state of each component
element has not been completely elucidated. It seems probable,
however, that each component is not simply present in the form of a
mere individual oxide but is chemically bonded with the other
component oxides.
It is well known that a catalyst system containing phosphorus and
molybdenum is effective for the gas phase oxidazation of acrolein
or methacrolein. However, phosphorus and molybdenum form very
complicated compounds depending on the mixing ratio, heat-treating
temperature and atmosphere employed.
In the method of preparing the catalyst of this invention, the
catalyst is heat-treated in an atmosphere of air or an inert gas at
a temperature of 300.degree. to 600.degree. C. for from 1 hour to
scores of hours. The heat-treating atmosphere influences the
resultant catalyst activities. An atmosphere of an inert gas such
as nitrogen, ammonia, carbon dioxide, carbon monoxide, a
hydrocarbon, helium, argon and the like produces a catalyst high in
activity.
The reason for the increase in catalyst activity has not been
completely elucidated, but it has been determined that when the
catalyst of the present invention is heat-treated in an atmosphere
of air, the color of the catalyst changes to yellow-green.
Moreover, after the catalyst has been used in the process of this
invention, the color changes to deep-blue and the phospho-molybdic
acid or salt thereof in the catalyst is reduced. On the other hand,
when the catalyst is heat-treated in an atmosphere of nitrogen gas,
the color changes to dark-green showing that the catalyst has been
further reduced. After the catalyst is used in the process, the
color returns to a deep-blue which shows that the catalyst is
oxidized by the oxygen in the reaction feed gas. From these facts,
it is believed that in the catalyst of the present invention, the
half-reduced phospho-molybdic acid or salt thereof is quite
significant for catalyst activity, and that the half-reduced
catalyst which comes from the reduced catalyst described above has
a higher activity than does one which comes from the aforementioned
oxidized catalyst.
When a catalyst containing phosphorus and molybdenum is used for a
gas phase oxidation, the activity and selectivity will often be
reduced by variations in the catalyst structure occurring with
increased use and reaction time. This tendency increases as the
reaction temperature is elevated.
The increase in catalyst activity, therefore, is an important
practical consideration because with higher activities the
oxidation reaction can be performed at lower temperature and the
catalyst lifetime can be prolonged.
Among the metals represented by X in the catalyst of the present
invention, rhodium is particularly preferred in respect of the
selectivity to methacrylic acid that is displayed.
The atomic ratio of the metal represented by Z must be within the
range of 0 to 6, especially 0.01 to 6, when molybdenum is 12. When
two or more of these metals are present, it is preferred that the
sum of the atomic ratio of the metals is within the above
range.
The preparation of the catalyst to be used in this invention can be
accomplished according to methods known to those skilled in the
art. For example, conventional methods such as evaporation-to
dryness, precipitation, oxide-mixing or the like can be used.
The catalyst components may be used on carriers or diluted with
such known inert carriers as silica, alumina, silica-alumina and
silicon carbide.
Various compounds can be used as starting materials for the
catalyst. These include, for example, nitrates, ammonium salts,
chlorides, oxides and heteropoly acids such as phosphomolybdic
acid.
The reactant unsaturated aldehyde may contain small amounts of
impurities which have no influence on the reaction, such as water
or a lower saturated aldehyde. The process of this invention is
especially effective for the oxidation of methacrolein.
Methacrolein which is obtained by the catalytic oxidation of
isobutylene or t-butyl alcohol can be used as is or alternatively
after being purified.
The concentration of the unsaturated aldehyde in the feed gas can
be varied within a broad range, but is preferably 1 to 20% by
volume, especially 3 to 15% by volume.
Molecular oxygen is used as the oxidant in the process of this
invention. Preferably, air is used from the economic viewpoint. If
necessary, an oxidant of air enriched with pure oxygen can also be
used. The concentration of oxygen in the feed gas, in terms of the
mole ratio relative to the unsaturated aldehyde, should be within
the range of 0.3 to 4, especially 0.4 to 2.5. The starting gaseous
mixture may be diluted with an inert gas such as nitrogen, steam,
carbon dioxide or the like.
The oxidation reaction is conducted under a pressure ranging from
atmospheric pressure to several atmospheres. The reaction
temperature may be chosen within the range of from 200.degree. to
500.degree. C., preferably 250.degree. to 400.degree. C. The
contact time is preably from 0.5 to 10 seconds.
In the process of this invention, both the conversion of
methacrolein and the selectivity to methacrylic acid are generally
above 80% by moles. This is very significantly higher than the
results observed for processes which use catalysts comprising P, Mo
and alkali metals or comprising P, Mo, alkali metals and silicon,
chromium, aluminum, germanium or titanium.
Having generally described this invention, a further understanding
can be obtained by reference to certain specific examples which are
provided herein for purposes of illustration only and are not
intended to be limiting.
In the following, the parts are by weight. The selectivity to the
unsaturated carboxylic acid is the ratio (%) of the molar amount of
the desired unsaturated carboxylic acid product to the molar amount
of the reacted unsaturated aldehyde.
EXAMPLE 1
42.4 parts of ammonium paramolybdate were dissolved in 85 parts of
water. A solution prepared by dissolving 9.75 parts of cesium
nitrate in 50 parts of water was added thereto. 0.56 part of solid
rhodium chloride was further added and was dissolved. Then, 4.61
parts of 85% phosphoric acid was added. The resulting mixed
solution was evaporated to dryness by heating with agitation. The
obtained cake was dried at 130.degree. C. for 16 hours, was
compression-molded, sieved to a 10 to 20 mesh per inch size and
then was calcined at 500.degree. C. under an air current atmosphere
for 2 hours to form a catalyst.
The composition of the catalyst was of P.sub.2 Mo.sub.12 Cs.sub.2.5
Rh.sub.0.1. This catalyst was packed in a fixed bed vessel and a
gaseous mixture of 5% of methacrolein, 10% of oxygen, 30% of steam
and 55% of nitrogen (all by volume) was fed into the vessel at a
reaction temperature of 325.degree. C. for a contact time of 3.6
seconds. The reaction gas discharged from the vessel was analyzed
by gas chromatography. The conversion of the methacrolein was 83.4%
and the selectivity to the methacrylic acid was 82.4%. Further,
acetic acid, carbon dioxide and carbon monoxide were produced. When
the reaction was continued under the same conditions for about 1600
hours, the conversion of the methacrolein was 83.0% and the
selectivity to the methacrylic acid was 82.2%.
EXAMPLES 2 AND 3
The following catalysts were prepared in the same manner as in
Example 1 except that the atmosphere of the calcination was varied.
These catalysts were used for oxidation of methacrolein under the
same conditions as in Example 1 except for the reaction
temperature.
The results of the experiments are summarized in Table I.
TABLE I
__________________________________________________________________________
conver- reaction sion of selectivity Ex- Catalyst Com- atmosphere
tempera- reaction metha- to metha- ample position of calcination
ture time crolein acid crylic acid No. (atomic ratio) of the
catalyst (.degree.C.) (hr) role in (%) (%)
__________________________________________________________________________
2 P.sub.2 Mo.sub.12 Cs.sub.2.5 Rh.sub.0.1 N.sub.2 295 4 82.1 83.1
1,600 82.3 83.0 3 " NH.sub.3 300 4 82.0 82.5 1,600 82.1 83.0
__________________________________________________________________________
EXAMPLES 4 TO 36
The following catalysts were prepared in the same manner as in
Example 1 except for the catalyst composition and the atmosphere of
calcination which are shown in Table II. These catalysts were used
for oxidation of methacrolein under the same conditions as in
Example 1 except for the reaction temperature.
The results are shown in Table II.
TABLE II
__________________________________________________________________________
conversion selectivity atmosphere reaction of metha- to metha-
Example Catalyst composition of calcination temperature crolein
crylic acid No. (atomic ratio) of the catalyst (.degree.C.) (%) (%)
__________________________________________________________________________
4 P.sub.2 Mo.sub.12 K.sub.2.5 Rh.sub.0.1 air 340 78.5 78.4 5
P.sub.2 Mo.sub.12 Rb.sub.2.5 Rh.sub.0.1 air 335 80.1 79.8 6
P.sub.1.5 Mo.sub.12 K.sub.2 Rh.sub.0.5 air 330 79.4 79.8 7 "
N.sub.2 290 80.3 80.0 8 P.sub.2 Mo.sub.12 Cs.sub.2 Ce.sub.0.5 air
320 82.4 81.8 9 " N.sub.2 290 81.8 82.0 10 P.sub.1 Mo.sub.12
Cs.sub.2.5 Zr.sub.0.5 air 325 82.5 82.5 11 " N.sub.2 295 82.0 81.9
12 P.sub.2.5 Mo.sub.12 Rb.sub.1 Cs.sub.1 air 330 83.1 82.2
Rh.sub.0.3 Ce.sub.0.2 13 P.sub.2.5 Mo.sub.12 Rb.sub.1 Cs.sub.1
NH.sub.3 295 82.8 82.5 Rh.sub.0.3 Ce.sub.0.2 14 P.sub.2 Mo.sub.12
Cs.sub.2 Rh.sub.0.1 Fe.sub.1 air 310 84.1 85.6 15 P.sub.2 Mo.sub.
12 K.sub.2 Rh.sub.0.1 Fe.sub.1 " 315 83.4 84.9 16 P.sub.2 Mo.sub.12
Rb.sub.2 Rh.sub.0.1 Fe.sub.1 " 310 81.2 84.6 17 P.sub.1 Mo.sub.12
K.sub.2.5 Rh.sub.0.05 Co.sub.0.5 " 305 81.3 83.2 18 P.sub.2
Mo.sub.12 Cs.sub.2 Rh.sub.0.05 Ni.sub.1 " 315 84.8 84.5 19 P.sub.2
Mo.sub.12 Cs.sub.2 Rh.sub.0.05 Zn.sub.1 " 320 82.7 83.3 20 P.sub.1
Mo.sub.12 Cs.sub.1 Rh.sub.0.3 Sb.sub.1 " 315 82.9 84.7 21 P.sub.1
Mo.sub.12 K.sub.1 Cs.sub.1 Rh.sub.0.1 Si.sub.2 " 315 83.1 84.2 22
P.sub.2 Mo.sub.12 Cs.sub.3 Rh.sub.0.1 Bi.sub.0.5 " 315 83.5 84.2 23
P.sub.2 Mo.sub.12 Cs.sub.3 Rh.sub.0.05 Cd.sub.0.5 " 310 82.5 84.0
24 P.sub.2 Mo.sub.12 Cs.sub.3 Rh.sub.0.03 U.sub.1 " 315 83.0 84.5
25 P.sub.2 Mo.sub.12 K.sub.2 Rh.sub.0.03 Mn.sub.0.3 " 320 83.3 83.7
26 P.sub.2 Mo.sub.12 K.sub.2 Rh.sub.0.03 Cu.sub.0.5 " 320 82.9 80.0
27 P.sub.2.5 Mo.sub.12 Cs.sub.2 Rh.sub.0.03 V.sub. 1 " 320 84.1
82.8 28 P.sub.1.5 Mo.sub.12 Cs.sub.1 Rh.sub.0.05 Nb.sub.1 " 315
82.4 84.6 29 P.sub.1.5 Mo.sub.12 Rb.sub.2 Rh.sub.0.05 Ta.sub.1 "
315 78.8 82.9 30 P.sub.1 Mo.sub.12 K.sub.1 Rh.sub.0.01 Fe.sub.0.5 "
310 81.0 85.4 Si.sub.0.5 31 P.sub.2 Mo.sub.12 Cs.sub.2 Rh.sub.0.01
Zn.sub.1 Sb.sub.1 " 315 83.5 84.1 32 P.sub.1 Mo.sub.12 Cs.sub.2
Rh.sub.0.01 Bi.sub.0.3 " 310 79.6 82.7 Cd.sub.0.7 33 P.sub.2
Mo.sub.12 Rb.sub.1 Cs.sub.1 Rh.sub.0.01 " 315 82.6 80.8 Mn.sub.0.5
Ta.sub.2 34 P.sub.1 Mo.sub.12 K.sub.2 Rh.sub.0.2 Fe.sub.0.7 " 310
84.5 85.2 Sb.sub.1 Bi.sub.0.3 35 P.sub.1.5 Mo.sub.12 K.sub.1.5
Rh.sub.0.2 " 310 82.2 84.0 Cd.sub.1 V.sub.0.4 U.sub.1 36 P.sub.2
Mo.sub.12 K.sub.2 Rh.sub.0.03 Co.sub.0.5 " 310 83.1 85.8 Zn.sub.0.5
Si.sub.0.3 Cu.sub.0.3
__________________________________________________________________________
EXAMPLES 37 TO 40
The catalysts of Examples 1, 2, 14 and 19 were used for the
oxidation of acrolein. A gaseous mixture of 5% of acrolein, 10% of
oxygen, 30% of steam and 55% of nitrogen (all by volume) was fed
into the vessel at the temperatures shown in the following Table
for a contact time of 3.6 seconds. The reaction gas discharged from
the vessel was analyzed by gas chromatography.
The results are shown in Table III.
TABLE III ______________________________________ con- reaction
version select- Ex- tempera- of ivity to ample catalyst composition
ture acrolein acrylic No. (atomic ratio) (.degree.C.) (%) acid (%)
______________________________________ 37 P.sub.2 Mo.sub.12
Cs.sub.2.5 Rh.sub.0.1 335 90.1 91.0 38 P.sub.2 Mo.sub.12 Cs.sub.2.5
Rh.sub.0.1 315 91.0 90.8 39 P.sub.2 Mo.sub.12 Cs.sub.2 Rh.sub.0.1
Fe.sub.1 310 90.5 92.6 40 P.sub.2 Mo.sub.12 Cs.sub.2 Rh.sub.0.05
Zn.sub.1 310 89.6 91.9 ______________________________________
Having now fully described the invention, it will be apparent to
one of ordinary skill in the art that many changes and
modifications can be made thereto without departing from the spirit
or scope of the invention as set forth herein.
* * * * *